All work to be done by licensed professional. WE KEEP GOING UNTIL YOU HAVE THE INFORMATION YOU NEED, I come and go. This is step ONE.
Defective electronics inside the thermostat is the 99% most likely cause....
we can do a few tests to prove if thats actually the case or not.
Test #1 follow the the thermostat wires where they come out of the wall next to the furnace or air handler
remove the service panel there, by lifting it up and pulling it out
tell me what colors the thermostat wires are attached in side the unit.
We can go from there